1. Field of the Invention
The present invention generally relates to stereoscopic image processing, and, more particularly, to an interleaved approach to depth-image-based rendering of stereoscopic images.
2. Description of the Related Art
Stereoscopic imagery is created by generating separate image frames for the left eye and the right eye, creating a three-dimensional viewing experience. In order to reduce the rendering and transmission time needed to generate two separate image streams, stereoscopic imagery may be accomplished by rendering images and depth information for one eye. Images for the second eye are then generated using a post-rendering process called depth-image-based rendering (DIBR). With DIBR, images are rendered for only one eye, thus reducing rendering time as compared rendering images for both eyes. Additionally, depth information consumes less space and compresses more efficiently than image information. Therefore, transmission of images plus depth information for a single eye consumes less bandwidth than transmission of images for two eyes.
With DIBR, image picture elements (pixels) for one eye undergo a reprojection step utilizing the depth frame to create image pixels for the second eye. Because each eye sees a slightly different view of a scene, some of the pixels in the image generated for the second eye may not map to a corresponding pixel in the image for the first eye. When this occurs, holes or gaps appear in the image generated for the second eye. This phenomenon is called disocclusion. Various approaches are used to remedy disocclusion, including techniques to minimize creation of holes and techniques to fill such gaps with plausible color information.
Creation of gaps may be minimized by smoothing the data in the depth frame. Depth frame smoothing reduces high frequency noise, which is the primary cause of holes in the generated image. Depth frame smoothing may also blend surrounding silhouette colors into gaps. As a result, the gaps are less noticeable, but the generated image may appear blurry or objects in the image that are near the gaps may appear to be unnaturally stretched. Alternatively, gaps may be filled using various approaches such as inward painting (inpainting) the gaps using neighboring pixels, using averaging filters, or filling the holes with constant colors. One drawback with these approaches is that the gaps are filled with image data that is not actually seen by the second eye, resulting in a less realistic appearance. Artifacts of these approaches may be more noticeable where gaps are relatively large and where objects are close to the eyes.
As the foregoing illustrates, what is needed in the art is an improved technique for generating stereoscopic images using DIBR.